Systems and apparatus to lubricate a gas turbine engine via an external pressure source

A gas turbine engine, comprising:

• a compressor section;
• a combustion section;
• a turbine section;
• one or more components operatively coupled with at least one of the compressor section, the combustion section, or the turbine section;
• a reservoir configured to store a lubricant;
• a supply pump configured to pump the lubricant from the reservoir to a component via a supply conduit;
• a scavenge pump configured to pump the lubricant from the component;
• and
• a valve fluidly coupled with the scavenge pump, the valve to control a flow of lubricant to the reservoir;
• and
• an external pressure source coupled with the valve, the external pressure source to provide a pressure to actuate the valve from a supply position to a bypass position, wherein in the bypass position the valve fluidly couples lubricant flowing through the scavenge pump into a bypass conduit, the bypass conduit extending from the valve to a location downstream of the supply pump.